Use Float32 to calculate colordiff for low precision colors

[kimikage]

This is a follow-up to PR #494.
For consistency with DE_2000, this allows Float32 to be used for other metrics.

[codecov]

Codecov Report

Merging #504 (9ed09ac) into master (15466d6) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #504      +/-   ##
==========================================
+ Coverage   93.80%   93.84%   +0.04%     
==========================================
  Files           9        9              
  Lines        1146     1154       +8     
==========================================
+ Hits         1075     1083       +8     
  Misses         71       71              

Impacted Files	Coverage Δ
src/differences.jl	99.29% <100.00%> (+0.04%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 15466d6...9ed09ac. Read the comment docs.

[kimikage]

Examples

julia> function cdiff(m)
           a = Colors.JULIA_LOGO_COLORS.red
           b = Colors.JULIA_LOGO_COLORS.purple
           println(colordiff(a, b, metric=m))
           println(colordiff(RGB{Float64}(a), RGB{Float64}(b), metric=m))
           println(colordiff(RGB{BigFloat}(a), RGB{BigFloat}(b), metric=m))
       end
cdiff (generic function with 1 method)

julia> cdiff(DE_2000())
33.82887
33.82887329869433
33.82887329869434796475792923435851027620015476174136875625922539498207369411706

julia> cdiff(DE_94())
38.23486
38.234862143090865
38.23486214309088608963095792665674301916407422865080768162621819010507168360492

julia> cdiff(DE_JPC79())
37.878086
37.87808541971468
37.87808541971468968166730168312403080137191745434699713648683643401155205874664

julia> cdiff(DE_CMC())
52.563896
52.563899827254474
52.5638998272545176069372623733566704452279622154186758390851358812518998154462

julia> cdiff(DE_BFD())
49.900528
49.90052646306692
49.90052646306697049716708771910579177559075682142050054874112972427357928337113